set rlim_fd_max = 4096
The server will raise the soft limit to the hard limit.
+Linux 2.2 -- [Tri]/Isomer
+The kernel has a kernel destination cache size of 4096. If the kernel sees
+more than 4096 IP's in 60s it warns 'dst cache overflow'. This limit can be
+changed by modifying /proc/sys/net/ipv4/route/max_size.
+A patch to select is also recommended if you have regular poll/select
+errors.